Coding expert Jonathan Hunt said: "Flash is notoriously insecure, doesn't run on mobile devices, and is largely redundant compared to the open web platform."
Both Mozilla's Firefox and Apple's Safari have recently announced a phasing out of Flash.
"Browser plugins, especially Flash, have enabled some of our favorite experiences on the Web, including videos and interactive content," Benjamin Smedberg, manager of Firefox quality engineering at Mozilla, said in a blog post this July. "But plugins often introduce stability, performance, and security issues for browsers. This is not a trade-off users should have to accept."
"Mozilla and the Web as a whole have been taking steps to reduce the need for Flash content in everyday browsing. Starting in August, Firefox will block certain Flash content that is not essential to the user experience, while continuing to support legacy Flash content. These and future changes will bring Firefox users enhanced security, improved battery life, faster page load, and better browser responsiveness," Smedberg said.
All internet browsers prioritise web-standards over propriatary technology such as Flash.
Former Apple CEO Steve Jobs famously loathed Flash and never added support for the technology on iPhones.
Android and iOS users were also confronted with errors when they tried to access the reports - the page was designed to prompt users to download an SAS app to use the site, but that prompt only showed a "blocked" message.
A police spokesman said they originally considered using HTML5 but opted for Flash because it was more likely to be commonly supported.
"We also wanted as wide a range of users as possible to access these reports, so we opted for Flash instead," the spokesman said.
"On balance Flash is best at this time."
Police said they anticipate changing to HTML5 "in future."
A spokesman did not comment on the website outage, but the tool is back online today after Police upgraded the website with more processing power.
Police have not responded to questions about the price of the project.